Reconsider the soft drink demand data in Table E4.5 and used in Exercise 4.31. a. Use the additive seasonal effects model for the first three years to develop a forecasting method for this data. How...

Reconsider the soft drink demand data in Table E4.5 and used in Exercise 4.31.

a. Use the additive seasonal effects model for the first three years to develop a forecasting method for this data. How well does this smoothing procedure work?

b. Make one-step-ahead forecasts of the last 12 months. Determine the forecast errors. How well did your procedure work in forecasting the new data?

c. Compare these forecasts with those found using Winters" multiplicative method in Exercise 4.31.

Exercise 4.31
Montgomery eta!. [1990] give four years of data on monthly demand for a soft drink. These data are given in Table E4.5. 4.32

TABLE E4.5 Soft Drink Demand Data